Firetube vs. Watertube Boilers: Which System Is Better for My Iowa Home?

If you’re wondering whether a firetube or watertube boiler system is better for your Iowa home, the answer is: it depends.

Ultimately, the best way to determine which type of boiler system you need is to consider the following factors:

Before we jump into comparing these two types of boilers, let’s briefly review how boilers work so you can better understand the differences between the systems.

All boilers heat water or produce steam to heat a home, but each kind works differently.

To simplify things, let's look at how the general boiler process works. Then, we'll go into more detail about the differences between firetube and watertube boilers.

A watertube boiler consists of metal tubes containing water set vertically inside a drum that also houses the burner. Once the system lights the burner, the flames, heat, and gases surrounding the tubes heat the water.

When the water reaches the correct temperature, it circulates through piping via circulator pumps. If the boiler is a steam boiler, the steam creates natural pressure to force itself to flow through the piping.

In contrast, a firetube boiler has horizontal tubes filled with heat from the burner flames instead of vertical metal tubes filled with water. These tubes run through the water vessel and heat the water via convection. Like the watertube boiler, steam flows naturally from its own pressure once the water reaches the correct temperature and circulates via pumps.

Now that you know how boilers work, let’s compare firetube and watertube boilers based on the three factors listed above.

Firetube boilers are usually less expensive than watertube boilers.

When you consider the cost of buying a new boiler for your Iowa home, you should think about the initial purchase price of the system as well as the cost for installation. A firetube’s design is considerably less complex than a watertube’s, contributing to its lower purchase price. Watertube boilers are also larger, and they contain more steel, so they are usually more expensive.

Beyond just the cost for the parts, installation costs for firetube and watertube boilers will also vary depending on the contractor you hire.

Typically, installing a firetube boiler is cheaper because it’s easier and requires less labor and time, while installing a watertube boiler usually requires extensive labor because the technician has to install the burner, fuel trains, controls, and boiler trim. In comparison, with a firetube boiler, these items are already factory installed and tested.

Before making your decision, you should call multiple Iowa contractors to get a few different installation quotes. Make sure they provide any estimates in writing too.

If you compare equally sized watertube and firetube boilers, a firetube boiler will save you more in annual fuel costs. But, you shouldn’t completely disregard a watertube boiler for this reason.

Watertube boilers heat less water at a time, respond more quickly to changes in demand and steam, and you can increase their heating capability by adding more tubes. They can also handle a more significant amount of pressure and higher temperatures compared to firetube boilers.

To help you determine which is best for your home, you can use Annual Fuel Utilization Efficiency (AFUE) ratings to measure a boiler’s efficiency. The AFUE essentially tells you how efficient the boiler is at converting the energy in its fuel into heat over a typical year.

For example, a 90% AFUE rating means that the boiler will convert 90% of the energy from its fuel into heat for the home. The other 10% gets lost via its chimney pipe or elsewhere.

Depending on the type of boiler you purchase, the efficiency rating will vary. Look for an EnergyStar rating on a boiler before buying, which indicates that it’s energy-efficient and, as a result, will save you money.

• If you’re shopping for an oil boiler, look for one that has an 87% AFUE rating or higher.
• If you’re shopping for a gas boiler, look for one that has a 90% AFUE rating or higher.

Overall, a firetube boiler will likely be cheaper to maintain.

Like any other appliance or household system, your boiler will need regular maintenance and cleaning to ensure it’s working correctly. When comparing maintenance costs for a firetube and watertube boiler over their lifespans, you’ll want to consider the frequency and cost of labor as significant factors.

Typically, firetube boiler maintenance will cost you less over time because:

Cleaning a firetube boiler is more manageable because a technician can do it from outside the unit rather than inside. Meanwhile, with watertube boilers, a tech must complete much of the cleaning from inside the unit, requiring more extensive labor and time to complete.

Firetube boilers have straight and simple tubes, making it easy for contractors to get local distributors for and replace within an hour. On the other hand, watertube boilers contain specially bent tubes that require a considerable amount of time to source and replace. In addition, if a failed tube is inside the unit where it’s hard to repair, the tech may have to replace several good tubes just to reach the defective one.

All boilers undergo rapid temperature changes with resulting thermal stress that can damage the boiler over time by causing cracks, leaky tube joints, and failed tubes. Imagine what would happen if you filled a cold glass with a hot liquid. It would crack, much like what would happen if you fill a hot boiler with cold water. The design of firetube boilers means that they aren't affected much by thermal stress, leading to fewer maintenance issues and repairs down the line, unlike watertube boilers.